Two molecules that possess identical chemical formulas with the same atoms bonded one to another but that differ in the manner that those atoms are arranged in space are referred to as stereoisomers. Stereoisomers that are mirror images of each other such that they are not superimposable one upon the other, because they have opposite configurations, are referred to as enantiomers. A mixture of equal parts of the two mirror image forms, or enantiomeric forms, is referred to as a racemic mixture.
Physiological activity has been shown to be closely related to the configuration of a molecule. For example, it is known that one enantiomeric form of adrenalin is over ten times more active in raising blood pressure than is the other form. Additionally, enzymes which catalyze chemical reactions in the body are frequently programmed to accept one enantiomeric form but not the other.
7-(Aminopyrrolidin-1-yl)naphthyridine carboxylic acids (Chu, U.S. Pat. No. 4,616,019, issued Oct. 7, 1986) and 7-(aminopyrrolidin-1-yl)quinolone carboxylic acids (Chu, U.S. Pat. No. 4,730,000, issued Mar. 8, 1988) are known to be antibacterial agents. A racemic mixture of 7-(3-aminopyrrolidin-1-yl)-1-(o,p-difluorophenyl)-1,4-dihydro-6-fluoro-4-o xo-1,8-naphthyridine-3-carboxylic acid has been shown to exhibit antibacterial properties. J. Med. Chem., 29, 2363 (1986).
A racemic mixture of 7-(3-aminopyrrolidin-1-yl)-1-(o,p-difuorophenyl)-1,4-dihydro-6-fluoro-4-ox o-1,8-naphthyridine-3-carboxylic acid is prepared by Reaction Scheme I as illustrated below: